title: Thermodynamics of oxygen binding to arctic hemoglobins. The case of reindeer.
abstract: The most surprising characteristic of reindeer hemoglobin (Hb) concerns its response to changes in temperature. Thus, the shape of the oxygen-binding curve is strongly temperature dependent due to the difference in the enthalpy of oxygenation between the T and R state of the molecule. In fact, delta H of oxygen binding to the T state is strongly exothermic whereas that of the R state is very close to zero or possibly positive after correction for the heat of oxygen solubilization. Moreover, the allosteric transition T0----R0 has been found to display a negative delta H and a contemporaneous decrease in entropy, a behavior which is precisely the opposite of what has been reported for other hemoglobins. As a whole, reindeer Hb represents a beautiful example of the significance that comparative studies may have in assessing the general validity of the main properties of the hemoglobin molecule.
authors.affiliation: Department of Experimental Medicine and Biochemical Sciences, II University of Rome, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Giardina
authors.forename: S G
authors.initials: SG
authors.lastname: Condò
authors.forename: R
authors.initials: R
authors.lastname: Petruzzelli
authors.forename: A
authors.initials: A
authors.lastname: Bardgard
authors.forename: O
authors.initials: O
authors.lastname: Brix
mesh_terms: D019794:2,3-Diphosphoglycerate; D000818:Animals; D001110:Arctic Regions; D004163:Diphosphoglyceric Acids / Q000378:metabolism; D006441:Hemoglobin A / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D008962:Models, Theoretical; D010108:Oxyhemoglobins / Q000378:metabolism*; D011487:Protein Conformation; D012053:Reindeer / Q000097:blood*; D013816:Thermodynamics
chemical_list: D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D010108:Oxyhemoglobins; D019794:2,3-Diphosphoglycerate; D006441:Hemoglobin A